System for cleaning fresh and fresh-cut produce

ABSTRACT

The system for cleaning fresh and freshly-cut produce is designed to clean produce as soon as practicable after the produce is cut. As the produce falls downwardly, a spray manifold directs a produce-washing liquid upwardly so that the produce-washing liquid directly sprays and impacts the falling produce. The impact of the produce-washing liquid causes the produce to tumble and the descent of the produce is slowed, and consequently the produce is thoroughly coated and cleaned by the produce-washing liquid. In an alternative embodiment, a suspending fluid (preferably air) is simultaneously directed to the falling produce to slow the descent of the produce and further ensure that the produce is thoroughly washed and directly sprayed by the produce-washing liquid.

REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.62/287,964 filed Jan. 28, 2016, which is incorporated herein byreference in its entirety.

FIELD OF THE INVENTION

The disclosed method and apparatus relate to a process for washing wholefresh and fresh-cut produce so that the produce organic exudate isremoved and segregated from the produce as soon as practicable aftercutting the produce, and foreign materials and microorganisms areremoved/inactivated. Specifically, the method and apparatus describedherein relate to a system for washing produce by directing a spray of aproduce-washing liquid onto fresh-cut (or uncut) produce that is fallingdownwardly. The system is designed so that as the produce falls, it isimpacted, reoriented, cleaned, and/or sanitized by the produce-washingliquid.

BACKGROUND OF THE INVENTION

Fresh-cut produce (including bagged salad, baby spinach, shredded, andsliced carrots, shredded lettuce and cabbage, diced and sliced onions,and other cut fruits and vegetables) is an approximately three billiondollar industry. Efficiently cleaning and processing fresh-cut produceis essential to product safety, product quality, and cost management. Asignificant portion of the cost of processing fresh-cut produce isrelated to (a) the amount of water used during the process, and (b) thecost of the chemicals (frequently chlorine) mixed with the water toproduce a sanitizing liquid.

In current fresh-cut processing, harvested produce is generally cut andthen washed to remove organic exudate (such as juices and/or a moreviscous pulpy matter) that has leaked from freshly-cut surfaces, as wellas field debris and soil particulates. This “organic exudate” reactsimmediately and continuously with chlorine and other sanitizers, andconsequently reduces the level of active (“free”) chlorine and othersanitizers in the washing solution. Free chlorine and other sanitizerscan be replenished through the “make-up” addition of chemicals, but thecontinuing accumulation of organic material in the wash solutionrequires the addition of ever-larger amounts of sanitizer chemicals inorder to maintain an adequate concentration of active sanitizer forsanitizing produce and preventing microbial cross-contamination.

When adequate sanitizer concentration is not maintained above a criticallevel, not only is the efficacy of microbial reduction diminished, butalso microbial survival in wash water is enhanced, which allowsmicrobial contamination of otherwise clean produce. This then results insignificant food safety and food quality problems. Additionally, someby-products from chlorination reactions with organic exudate are knownor suspected carcinogens, and the accumulation of large amounts oforganic material in the wash water leads to increases in their rates offormation, and to higher residual levels in the final product. Thepresence of these by-products prompted the European Union to prohibitthe use of chlorinated solutions for produce washing. Thus, early andeffective removal of organic exudate is critical.

Effective microbial inactivation in fresh-cut produce washing depends ona number of factors, including sanitizer concentration, exposure time ofthe produce to the washing solution, and the degree of agitation andturbulence experienced by the produce. Sanitizer concentration andexposure time are important because there is a strong relationshipbetween these factors and the desired outcomes, including microbialinactivation and maintenance of product quality.

If the combination of sanitizer concentration and exposure time isinsufficient, inadequate microbial inactivation is achieved. On theother hand, if the combination of sanitizer concentration and exposuretime is excessive, product damage will occur. Agitation and turbulenceare also important because they break up “clumps” of produce and alsoreduce the thickness of the “stagnant” boundary layer on the producesurface through which the sanitizing agent must penetrate in order to beeffective.

In the prior art, washing of fresh-cut produce is typically conducted ineither a continuous, semi-batch, or batch process. In continuousprocesses, fresh-cut produce is either submerged in a washing solutionthat flows through a flume, or resides on a moving belt that issubjected to a sprayed washing solution. In the former case, the meanexposure time of the produce to the washing solution is given by thevolume of the flume divided by the volumetric flow rate through theflume. In the latter case, the exposure time of each piece of produce isgiven by the length of the moving belt, divided by the linear velocityof the belt.

For spray washing on a belt, attempts to increase the exposure timerequire either a wider belt moving more slowly, or a longer belt. Sincehorizontal space is severely constrained in most of the fresh-cutprocessing facility in the United States, neither approach is a viableoption. U.S. Pat. No. 9,326,543 to McEntire and U.S. Pat. No. 6,626,192to Garcia disclose (primarily) spray-type systems where produce on aperforated conveyor is sprayed from both above and below the conveyor.Note that, although sprayers disclosed in the prior art are directedupwardly at the bottom of a produce conveyor, the sprayers are notpositioned to directly spray produce as it falls downwardly through theair above the conveyor.

For flume washing, attempts to increase the exposure time require eithermore pieces of equipment, each with less throughput, or equipment withlarger dimensions. U.S. Pat. No. 8,646,470 to Bajema is an example of a(primarily) flume type wash system.

Continuous-flume washing has several important limitations. First, tocontrol the cost of water usage and the energy to chill the water, washwater in the flume system is often reused, leading to a significantaccumulation of organic exudate along with field debris and soilparticulates. The organic constituents react rapidly and chemically withchlorine, thereby reducing the amount of free chlorine. The accumulationof exudate and other contaminants also allows the formation ofchlorinated by-products, and makes it difficult to maintain the chlorineconcentration at a level sufficient to achieve microbial inactivation.

Second, reuse of process water, especially in the turbulent mixingenvironment of a large flume, can lead to cross-contamination. Pathogensand other microbial species are spread in the turbulently flowingliquid, and thus further transferred to other pieces of produce. Insemi-batch and batch washing, the same tank of sanitizing liquid istypically used to wash many batches of produce, with the potential forconsiderable cross-contamination.

The need exists for a method to quickly and efficiently remove organicexudate, field debris, and soil particulates from freshly-cut producewhile minimizing both the use of chlorine (or other sanitizers) and thevolume of water used in the washing process, while (simultaneously)effectively cleaning the produce. In accordance with the current“inflight washing process,” immediately after the produce is cut, it isallowed to fall through a produce chute, such that as the producedescends, its fall is retarded by a generally upwardly flow ofproduce-washing liquid, and/or by a generally upwardly flow of air.

The upward flow of liquid and/or air causes the produce to reorient ortumble as it falls, and also retards the generally downward motion ofthe produce, thus increasing the exposure time to the liquid. These twofactors, singly, or in combination, increase the likelihood that eachpart of each piece of produce is thoroughly washed and exposed to thesanitizing liquid.

Although the exposure time is relatively short, the reorienting“tumbling” motion of the freshly-cut produce as it falls through anupward flow of liquid and/or air leads to more effective producesanitization than current industry practices. Further, after the fallingproduce lands, it can be quickly and effectively separated from theproduce-washing liquid, which now includes dissolved and suspendedorganic exudate, field debris, and soil particulates.

SUMMARY OF THE INVENTION

This disclosure is directed to a system and method for cleaning andsanitizing produce. In accordance with the current system and method, afeeder system is positioned above a produce-washing liquid sprayer. Asthe produce falls from the feeder system, the produce-washing liquidsprayer directs a spray of produce-washing liquid generally upward, sothat as the produce-washing liquid directly sprays and impacts thefalling produce, the produce tumbles and descent of the produce isslowed, and consequently the produce is thoroughly coated and cleaned bythe produce-washing liquid. In at least one alternative embodiment, anair flow is also directed upwardly to further slow the descent of theproduce and thereby increase the tumbling motion of the produce as wellas the time that the produce is exposed to the produce-washing liquid.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view of the produce chute.

FIG. 2.A. is a partial sectional view along the sectional line II shownin FIG. 1.

FIG. 2.B. is a partial sectional view of an alternative embodiment.

FIGS. 3-6 are graphical representations of test data collected by theinventors. Specifically, the inventors tested produce-washing liquidcollected below a perforated conveyor belt typical of conventionaloverhead produce spray operations (shown as “spray” in FIGS. 3-6), andcompared the characteristics of the “spray” produce-washing liquid withthe characteristics of the produce-washing liquid collected below thesubstrate (reference number 23, as shown in FIG. 1) per the methoddescribed herein (shown as “inflight” in FIGS. 3-6). FIGS. 3-6demonstrate, collectively, that the “inflight” invention (describedherein) performed more effectively in removing the organic material thanthe conventional spray with all other conditions held the same (e.g.,same amount of produce-washing liquid). Specifically:

FIG. 3 is a diagram showing chlorine demand for produce-washing liquidcollected from the conventional spray process, as compared to chlorinedemand for produce-washing liquid collected from the “inflight” processdescribed herein.

FIG. 4 is a diagram showing chemical oxygen demand (COD) forproduce-washing liquid collected from the conventional spray process, ascompared to COD for produce-washing liquid collected from the “inflight”process described herein.

FIG. 5 is a diagram showing absorbance (254 nm) for produce-washingliquid collected from the conventional spray process, as compared toabsorbance (254 nm) for produce-washing liquid collected from the“inflight” process described herein.

FIG. 6 is a diagram showing turbidity for produce-washing liquidcollected from the conventional spray process, as compared to turbidityfor produce-washing liquid water collected from the “inflight” processdescribed herein.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

As generally shown in FIG. 1, the method and apparatus described hereincomprises an “inflight produce washing system” 20 that is configured toclean produce. The system is described as an “inflight” system because afeeder system renders the produce airborne so that the produce iscleaned as it falls.

As shown in FIGS. 1 and 2.A., the inflight produce cleaning system 20comprises a produce chute 22. The produce chute 22 is designed togenerally funnel produce 30 downwardly in the direction of the arrows24. (Note that, although multiple chunks of cut produce 30, are shown inFIG. 2.A., for simplicity, only a few exemplary chunks 30 are labeledwith reference numbers.) A spray manifold 26 is positioned within theproduce chute 22. A plurality of upwardly oriented sprayers 28 isarranged on an upper surface of the spray manifold 26. In the preferredembodiment, the sprayers 28 direct a produce-washing liquid generallyupwardly (i.e., the produce-washing liquid has an “upward velocitycomponent”) so that as the produce falls, the produce-washing liquiddirectly sprays and cleans the produce. The fall of the produce 30 isultimately arrested by a substrate 23.

FIG. 2.B. shows an alternative embodiment wherein the modifiedproduce-washing system 40 comprises an upper manifold/apparatus 42 thatsprays a suspending fluid (such as air), and a lower manifold/apparatus44 that sprays produce-washing liquid. The purpose of the upper airspray manifold/apparatus 42 is to provide an air cushion that slows thedescent of fresh-cut produce 30 and lengthens the time that theproduce-washing liquid is in contact with the produce 30. Theupwardly-directed air also further facilitates the tumbling motion ofthe produce 30 so that the produce 30 is more thoroughly exposed to theproduce-washing liquid and is thereby cleaned by the produce-washingliquid.

For the purposes of this disclosure, a “produce-washing liquid” isdefined as any liquid used to clean, wash, or sanitize produce. The“produce-washing liquid” may include water either with or withoutadditive chemicals/substances. Some additive chemicals/substances mayinclude chlorinated or ozonated water, (sometimes with a surfactant) andother similar materials intended to clean, sanitize, and/or help processproduce.

A “suspending fluid” is defined as upwardly directed air, or other gas,or produce washing liquid, directed to the falling produce, to retardthe rate at which the produce falls—primarily for the purpose of causingthe produce to tumble and extending the time that the produce is exposedto the produce-washing liquid.

A “feeder system” is defined as any arrangement or assembly that causesproduce to fall/become airborne. As shown in FIG. 1, in the preferredembodiment, the feeder system 25 comprises an exit chute of a producecutter. Although FIG. 1 schematically shows the feeder system 25 asrelatively close to the produce chute 22, in the preferred embodiment,there is sufficient separation between the feeder system 25 and theproduce chute 22 so that after the produce 30 leaves the feeder system,the outer surface of the produce 30 is coated with produce-washingliquid as the produce 30 falls downwardly toward the produce chute 22(see FIG. 2.A). Note that the produce chute 22 is “bottomless” so thatthe produce 30 falls through the chute 22 and lands on the screen 23, asbest shown in FIG. 2.A.

A “sprayer” is defined as essentially anything that sprays. The term“sprayer” includes all types of nozzles (including jet nozzles), as wellas configurations that only comprise an aperture and may not include aconventional nozzle at all.

A flow with an “upward velocity component” is defined as a generallyupward flow that is directed so that the flow is at least 1 degree abovehorizontal.

“Cleaning the produce/fresh-cut produce/freshly-cut produce” is definedas at least partially removing the field debris, soil particles, andorganic exudate from the cleaned item.

“Organic exudate” is defined as the juices and/or a more viscous pulpymatter exuded from cut produce.

“Fresh produce” is defined as fruits and vegetables that are freshlyharvested or are still within a few days after harvesting, and have notbeen cut or subjected to any other form of size reduction.

“Fresh-cut produce” is defined as produce that has recently been removedfrom a field environment, and has been washed/sanitized, and packagedfor direct human consumption. Other items of fresh-cut produce include“minimally processed”, lightly processed”, and/or “ready-to-eat”produce. Examples may include cut lettuce, shredded carrots, dicedonions, and sliced apples. Washed, packaged, and ready-to-eat babyspinach and spring mix are also included in this category, althoughtheir preparation does not necessarily involve cutting at the processingplant.

“Freshly-cut produce” is a subset of fresh-cut produce and is defined asproduce where the produce item itself is freshly cut into smallerportions.

The term/phrase “directly sprays” means that (for example) producesprayers are positioned to directly spray the produce—and consequentlydo not “indirectly” spray the produce through a perforated conveyor beltor through any other intervening obstruction (i.e., the sprayers do not“indirectly spray” the produce). Sprayers “directly spray” produce whentheir spray is unobstructed by any type of conveyor belt/mechanism orany other object positioned between the sprayer and the produce thatdeflects or obstructs the spray.

In the preferred embodiment, the produce chute 22 is shaped like ahollow, truncated, and inverted cone. In alternative embodiments, theproduce chute 22 may have any form known in the art consistent withaccommodating the manifold 26. In further alternative embodiments, theproduce chute 22 may be absent completely. Similarly, in the preferredembodiment, the spray sprayers 28 (which may be jet spray nozzles) areconfigured to impart significant upward velocity to the suspending fluidso that the generally downward motion of the falling produce issignificantly retarded and so that the produce “tumbles” as it falls, soas to be thoroughly coated by and exposed to the liquid.

In alternative embodiments, the sprayers 28 (which may be nozzles) arecomprised of specifically shaped apertures in the upper portion of themanifold 26 so that the nozzles 28 do not extend above the upper surfaceof the manifold 26. In further alternative embodiments, some of thenozzles 28 may emit air rather than liquid washing solution so that acombination of air and washing liquid impacts the falling produce 30.

Although FIGS. 1, 2.A., and 2.B. show one or two azimuthal manifolds 26,42, 44 positioned in a circular, ring-like arrangement near the top ofthe produce chute 22, in alternative embodiments, there may be multiplemanifolds 26, 42, 44, and the manifold(s) may be positioned anywhere on,above, or below the chute 22. Additionally, all manifolds 26, 42, 44 mayemit produce-washing liquid, or two (or more) manifolds may emitproducing washing liquid and one (or more) manifold may emit asuspending fluid. Further, the manifolds 26, 42, 44 may be noncircularand instead, may have any shape known in the art and may (or may not) bepositioned on the boundary of the produce chute. In addition to beingpositioned horizontally (as shown in FIGS. 1, 2.A., and 2.B.), themanifold(s) may be oriented in any direction, including vertically.

FIG. 2.B. is described (above) as being configured so that suspendingfluid is sprayed from the upper sprayer/manifold 42 near the top of theproduce chute 22, and the produce cleaning liquid is sprayed from thelower sprayer/manifold 44 positioned lower in the produce chute 22.However, in alternative embodiments, the configuration may be reversedso that the produce-washing liquid is sprayed from the upper manifold42, and suspending fluid is sprayed from the lower manifold 44.

Further, in the preferred embodiment, the substrate 23 is comprised of amesh, grate, or other filtering material that allows liquids (such aswater, sanitizing liquid, including dissolved and suspended organicexudate, field debris, and soil particulates) to drain through thesubstrate 23 material and separate from the produce 30. The substrate 23may be a portion of a conveyor assembly or other mechanism associatedwith processing freshly-cut produce.

As best shown in FIG. 1 and FIG. 2.A., in operation, produce 30 isexpelled from a feeder assembly 25. As the produce 30 falls through theair in the direction of the arrows 24, nozzles 28 directly sprayproduce-washing liquid which impacts the freshly-cut produce 30, therebycausing the produce 30 to tumble in a generally downward motion. As theproduce 30 continues to fall, the produce 30 is ultimately funneleddownwardly by a bottomless produce chute 22, and onto a porous substrate23 where the produce-washing liquid (including any liquid now comprisingdissolved and suspended organic exudate and field debris) drains awayfrom (and is segregated from) the freshly-cut produce 30.

As shown in FIG. 2.B., in an alternative embodiment, a suspending fluidis sprayed from a upper sprayer/spray manifold 42 while theproduce-washing liquid is sprayed from a lower spray manifold 44. Thesuspending fluid (preferably air) further retards the downward motion ofthe freshly-cut produce 30 and increases the tumbling motion of theproduce 30 so that the produce 30 is more thoroughly exposed to thedirect produce-washing liquid spray 32.

In operation, one or more inflight wash systems 20, 40 may be arrangedin series to effectively ensure that the produce is thoroughly cleansed.Further, the inflight washing systems 20, 40 may be used either alone orin combination with other more conventional spraying or flume washingsystems—as required for the needs of a particular user/application.

For the foregoing reasons, it is clear that the method and apparatusdescribed herein provides an innovative system for cleaning produce. Thecurrent system may be modified in multiple ways and applied in varioustechnological applications. The disclosed method and apparatus may bemodified and customized as required by a specific operation orapplication, and the individual components may be modified and defined,as required, to achieve the desired result. Although the materials ofconstruction are not described, they may include a variety ofcompositions consistent with the function described herein. Suchvariations are not to be regarded as a departure from the spirit andscope of this disclosure, and all such modifications as would be obviousto one skilled in the art are intended to be included within the scopeof the following claims.

1. A produce cleaning system comprising a feeder system positioned abovea produce-washing liquid sprayer wherein, as the produce falls throughthe air from the feeder system, the produce-washing liquid sprayerdirects a spray of produce-washing liquid upward through the air, sothat as the produce-washing liquid directly sprays and impacts thefalling produce, the produce tumbles through the air and descent of theproduce is slowed, and consequently the produce is thoroughly coated andcleaned by the produce-washing-liquid.
 2. (canceled)
 3. (canceled) 4.(canceled)
 5. The system of claim 1, wherein the produce-washing liquidcomprises a liquid solution of chlorine or other sanitizer.
 6. Thesystem of claim 1, wherein the produce comprises fresh-cut produce. 7.The system of claim 1, wherein the produce comprises freshly-cutproduce.
 8. The system of claim 1, wherein the produce-washing liquidsprayer directly sprays the produce-washing liquid from a spraymanifold, the spray manifold being positioned in a produce chute. 9.(canceled)
 10. The system of claim 1, wherein the system furthercomprises a produce chute positioned so that the produce falls into thechute.
 11. The system of claim 10, wherein the produce chute has ahollow, truncated and inverted cone shape.
 12. The system of claim 10,wherein the produce chute has a round cross section so that produce isfunneled downwardly.
 13. The system of claim 8, wherein the manifoldcomprises nozzles that spray the produce washing liquid with an upwardvelocity component.
 14. (canceled)
 15. The system of claim 8, whereinthe manifold system extends horizontally and is concentric to walls ofthe chute.
 16. The system of claim 1, wherein the system furthercomprises a substrate positioned so that the cleaned produce ultimatelylands on the substrate and the produce-washing liquid drains away fromthe substrate. 17.-28. (canceled)